First please, it is Silversea not Silverseas.
And yes, it’s true that SS is the most formal with suit and tie required on formal nights in most venues however many people can make it work just fine with sport coat, tie and dark pants. La Terrazza and The Grill are informal attire required on formal nights. The excellent room service is also not a bad option on those few formal nights. Expedition cruises do not have a formal requirement nor do the Med cruises of 7 days or fewer. Seems like SS is beginning to relax the dress code a bit. Is the cruise you are considering an expedition cruise?
Outstanding service is evident on SS ships and you can avail yourself of as much pampering as you can tolerate but be assured that you will never get a chance to pour your water yourself!